[TowerTalk] FW: how long could be the mast ???

[Matt]

Hi Doug,

The answer will depend on the wind load area of your antennas, their
position on the mast, and the maximum wind speed that you wish to sustain.
I can tell you that even schedule 160 (extra heavy wall) 1.5" water pipe
will not support a lot of mast height with any significant antenna wind
loads at the top.  The problem is that water pipe is generally fabricated
from ASTM A53 or A106 mild steel, and only has about 35,000 psi of yield
strength (compared to 80,000+ psi for high strength steel alloys typically
used for tower masts).   The only good news is that the mild steel still has
pretty good toughness, which means that although it bends relatively easily,
it also can bend considerably before it ultimately breaks.  If you want to
pursue it, email me directly with the dimensions (tube diameters, lengths,
and element spacing) of you antennas and I'll run some numbers to get an
approximate answer for you.

By the way, haven't QSO'd with you since 2001-2003...  it's been a long
time....  :)

73
Matt
KM5VI




-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
Douglas Ruz (CO8DM)
Sent: Wednesday, December 02, 2015 9:03 PM
To: towertalk at contesting.com
Subject: [TowerTalk] how long could be the mast ???

Hi,

I am planning install an small tower for small yagis fixed to EU.

I have only 2 tower sections (10 ft each) and a 18 ft mast (galvanized water
pipe 1 1/4 or 1 1/2 " and 1/4 inch wall) for that project...how long could
be the mast ???...14 ft??...12 ft ???...

I would like install a 2 elem homebrew 20m yagi on top of the mast and 3
elem homebrew 15m yagi below and maybe 4 elem 10m yagi attach to the top of
the tower (not in the mast)....so, the mast will support 2 antennas...the
tower has one set of guys near the top.

any idea???

Thanks,

73....Douglas, CO8DM

"No creo que haya alguna emoción más intensa para un inventor que ver alguna
de sus creaciones funcionando. Esa emoción hace que uno se olvide de comer,
de dormir, de todo." - Nikola Tesla 

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